4. CALIBRATION CORRECTION CHART
READING
(fpm)
CORRECTION
READING
(fpm)
CORRECTION 50
+ 15
500
- 5 75
+ 15
550
- 8
100
+ 14
600
- 10
125
+ 14
700
- 15
150
+ 14
800
- 20
175
+ 13
900
- 25
200
+ 12
1000
- 30
250
+ 11
1200
- 35
300
+ 10
1400
- 45
350
+ 5
1600
- 50
400
1800
- 60
450
- 2
2000
- 65

5. Air Velocity = Reading + Correction
CALIBRATION CORRECTION CHART
Air Velocity = Reading + Correction
READING
(fpm)
CORRECTION
READING
(fpm)
CORRECTION 50
+ 15
500
- 5
R = 600 75
+ 15
550
- 8 1
R = reading on anemometer
R = 620 fpm
100
+ 14
600
- 10
C = - 10 1
125
+ 14
700
- 15
C = - 15
150
+ 14
800
- 20 2
175
+ 13
900
- 25
R = 700
200
+ 12
1000
- 30 2
250
+ 11
1200
- 35
Interpolation Formula
300
+ 10
1400
- 45
350
+ 5
1600
- 50
400
1800
- 60
(C - C )
450
- 2
2000
- 65 2 1
C =
x (R - R ) + C 1 1
(R - R ) 2 1
((-15) - (-10))
C =
x ( ) + (-10) = -11 fpm
( )
Air Velocity = 620 fpm + (- 11 fpm) = 609 fpm

6. Medium Velocity Air Measurements
(anemometers)
CALIBRATION CORRECTION CHART
A = W x H
H + H + H 1 3 2
Average H =
6.2’
5.8’
18.7’
The dimensions of
the mine entry were
measured.
READING
(fpm)
R = reading on
anemometer
R = 380 fpm
CORRECTION
READING
(fpm)
CORRECTION 50
+ 15
500
- 5 75
+ 15
550
- 8
100
+ 14
600
- 10
125
+ 14
700
- 15
150
+ 14
800
- 20
175
+ 13
900
- 25
200
+ 12
1000
- 30
250
+ 11
1200
- 35
300
+ 10
1400
- 45
350
+ 5
1600
- 50
400
1800
- 60
450
- 2
2000
- 65
Interpolation Formula
C =
(C - C ) 2 1
(R - R )
x (R - R ) + C
Air Velocity = Reading + Correction
q = V x A

7. Medium Velocity Air Measurements
(anemometers)
CALIBRATION CORRECTION CHART
READING
(fpm)
R = reading on
anemometer
R = 380 fpm
CORRECTION
READING
(fpm)
CORRECTION
6.2’
5.8’
5.8’ 50
+ 15
500
- 5 75
+ 15
550
- 8
18.7’
100
+ 14
600
- 10
125
+ 14
700
- 15
150
+ 14
800
- 20
H + H + H 1 3 2
Average H =
175
+ 13
900
- 25
R = 350
200
+ 12
1000
- 30 1
250
+ 11
1200
- 35
C = + 5
300
+ 10
1400
- 45 1
350
+ 5
1600
- 50
C = 0
400
1800
- 60 2
6.2’+5.8’+5.8’ 3
Average H =
450
- 2
2000
- 65
= 5.9’
R = 400 2
Interpolation Formula
A = W x H = 18.7’ x 5.9’ = 110 sq.ft.
C =
(C - C ) 2 1
(R - R )
x (R - R ) + C
q = V x A
((0) - (+ 5))
q = 382 fpm x 110 sq.ft.
C =
x ( ) + (+ 5) = + 2 fpm
( )
q = 42,020 cfm
Air Velocity = 380 fpm + (+ 2 fpm) = 382 fpm

8. Medium Velocity Air Measurements
(anemometers)
CALIBRATION CORRECTION CHART
A = W x H
H + H + H 1 3 2
Average H =
3.5’
3.4’
3.3’
20.2’
The dimensions of
the mine entry were
measured.
READING
(fpm)
R = reading on
anemometer
R = 310 fpm
CORRECTION
READING
(fpm)
CORRECTION 50
+ 15
500
- 5 75
+ 15
550
- 8
100
+ 14
600
- 10
125
+ 14
700
- 15
150
+ 14
800
- 20
175
+ 13
900
- 25
200
+ 12
1000
- 30
250
+ 11
1200
- 35
300
+ 10
1400
- 45
350
+ 5
1600
- 50
400
1800
- 60
450
- 2
2000
- 65
Interpolation Formula
C =
(C - C ) 2 1
(R - R )
x (R - R ) + C
Air Velocity = Reading + Correction
q = V x A

9. Medium Velocity Air Measurements
(anemometers)
CALIBRATION CORRECTION CHART
READING
(fpm)
R = reading on
anemometer
R = 310 fpm
CORRECTION
READING
(fpm)
CORRECTION
3.5’
3.4’
3.3’ 50
+ 15
500
- 5 75
+ 15
550
- 8
20.2’
100
+ 14
600
- 10
125
+ 14
700
- 15
150
+ 14
800
- 20
R = 300
H + H + H 1 3 2
Average H =
175
+ 13
900
- 25 1
200
+ 12
1000
- 30
250
+ 11
1200
- 35
C = + 10 1
300
+ 10
1400
- 45
C = + 5
350
+ 5
1600
- 50 2
400
1800
- 60
3.5’+3.4’+3.3’ 3
Average H =
R = 350
450
- 2
2000
- 65 2
= 3.4’
Interpolation Formula
C =
(C - C ) 2 1
(R - R )
x (R - R ) + C
A = W x H = 20.2’ x 3.4’ = 69 sq.ft.
q = V x A
C =
((+ 5) - (+ 10))
( )
x ( ) + (+ 10)
q = 319 fpm x 69 sq.ft.
q = 22,011 cfm
C = + 9 fpm
Air Velocity = 310 fpm + (+ 9 fpm) = 319 fpm